DEOEC Institute of Oncology Department of Radiotherapy.
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Transcript of DEOEC Institute of Oncology Department of Radiotherapy.
DEOEC Institute of OncologyDepartment of Radiotherapy
Radiology: diagnosisRadiotherapy: part of active oncotherapy (oncoradiology, radiation oncology)Oncology:chemotherapy
The branch of clinical medicine which uses ionising radiation, either alone or in combinations with other modalities, for the treatment of patients with cancer (or benign diseases). It includes responsibility for the treatment, follow up and supportive care of the patient as an integral of the multidisciplinary management of patients.
external beam radiation is delivered from outside the body by using a machine to aim high-energy rays (x-rays, gamma rays or photons). TELETHERAPY
internal radiation is delivered from inside the body by placing radioactive material, sealed in catheters or seeds, directly into the tumor. BRACHYTERAPY
1. „Direct hit”2. „Activated water”
1. „Direct hit”2. Activated
water O2 is
necessary
H2O
H+ OH- e-
H2 H2O2 H2O
oxidation
reduction
1. Lethal damage2. Sublethal damage
a) loss of reproductibility apoptosis
b) Repairc) Reoxigenistaiond) Repopulatione) Redistribution
1. Lethal damage2. Sublethal damage
a) loss of reproductibility apoptosis
b) Repairc) Reoxigenistaiond) Repopulatione) Redistribution
1. Lethal damage2. Sublethal damage
a) loss of reproductibility apoptosis
b) Repairc) Reoxigenistaiond) Repopulatione) Redistribution
EXCISIONS REPAIR
EndonucleazExonucleaz
↓Polymeraz
Liaz
MISMATCH REPAIR
1. Lethal damage2. Sublethal
damagea) loss of reproductibility
apoptosisb) Repairc) Reoxigenistaiond) Repopulatione) Redistribution
G. Steel, Basic Clinical Radiobiology 1997, second edition
In vitro effect of hypoxic conditionson radiation-induced cellular lethality
Cells are much more sensitive to x-rays in the presence of molecular oxygen than in its absence. The ratio of doses under hypoxia to those under oxia necessary to produce the same level of cell killing is close to 3.
OER = 2.8
Hypoxicoxic
50 1510 2520 30
0.001
0.01
0.1
1
10
Survi
ving f
ractio
n
Radiation dose (Gy)
OER (Oxygen enhancement ratio) = Radiation dose in hypoxia/ Radiation dose in air
1. Lethal damage2. Sublethal damage
a) loss of reproductibility
apoptosisb) Repairc) Reoxigenistaiond) Repopulatione) Redistribution
Hypoxia in tumors can results from two quite different mechanisms: chronic and acute hypoxia
Horsman MR and Overgaard J. 1992; Eur J. Cancer 28: 717-8
ChronicallyHypoxic Cells
AerobicCells
FunctionalBlood Vessel
NecroticCells
Acutely HypoxicCells
1. Isotopes isotope halfing time energy
(MeV) Ra-226 1626 y 0,830 Co-60 5,26 y 1,250 Ir-192 74,2 d 0,380 J-125 60,2 d 0,028
2. Cobalt unit Gamma-ray (photons)
Co60→ gamma-photons
3. Linear acceleratorPhotons and electrons
Precisely locate the target Hold the target fixed Accurately aim the radiation beam Shape the radiation beam to the target Deliver a radiation dose that damages
abnormal cells yet spares normal cells
Topometric-CTNo contrast media
Image fusions
GTV: gross tumor volume macroscopic tumor or tumor bed
CTV: clinical target volume: GTV+1-2 cm safety margin –microscopic tumor spreading-
PTV: planning target volume: CTV+0,5-1 cm movements of organs or breathing
Postop.Cervical cancer
3D –Target Volumes
MLC (multileaf collimator system)
TELETHERAPY: Fixed beam irradiation : direct field opposed fields 4 or more fields
TELETHERAPY: Fixed beam irradiation : direct field opposed fields 4 or more fields
BRACHYTHERAPY: Intracavital Intersticial
BRACHYTHERAPY: Intracavital Intersticial
EX. 1
EX.2
EX. 3
EX. 4
EX.5
Positioning, immobilisation devices Thermoplastic masks
Breast-boards
Conventional dose: 1,8-2 Gy/day, 5 day/week 2-7
week
Tumor killing doses: 30-78 Gy - hystology, tumor
type
- TNM stage,
KPS, ECOG
- indications
(neoadjuvant, adjuvant,
definitive, palliative)
- combinations
(RKT)
Conventional dose: 1,8-2 Gy/day, 5 day/week 2-7
week
Tumor killing doses: 30-78 Gy - hystology, tumor
type
- TNM stage,
KPS, ECOG
- indications
(neoadjuvant, adjuvant,
definitive, palliative)
- combinations
(RKT)
Tolarance of normal tissues (risk organs)
DVH: Dose-volume histograms
1. Simulation, positioning2. Topometric CT3. Treatment plan4. Resimulation5. Verification6. Treatment
1. Simulation, positioning
2. Topometric CT3. Treatment plan4. Resimulation5. Verification6. Treatment
1. Simulation, positioning
2. Topometric CT/MR
3. Treatment plan4. Resimulation5. Verification6. Treatment
1. Simulation, positioning
2. Topometric CT/MR
3. Treatment plan4. Resimulation5. Verification6. Treatment
Pictor 3D laser system
IsocenterVirtual point
1. Simulation, positioning
2. Topometric CT/MR
3. Treatment plan4. Resimulation5. Verification6. Treatment
RESULTS: 1. LTC : CR (4 mts) PR (-25-50%)
NC PD
2.Survival: Overal, Disease free, TTP
SIDE EFFECTS : early late local inflammation fibrosis
general weakness disfunction